The processes of cumene oxidation to cumene hydroperoxide (CHP) and subsequent acid-catalyzed (by sulfuric acid) CHP cleavage give rise to target products such as phenol and acetone, a valuable byproduct, such as alpha-methylstyrene (AMS), and also undesirable waste products. In such processes, salts of mostly sodium composition, such as sodium sulfate and sodium bisulfate, as well as salts of organic acids, mainly of formic, acetic, propionic, and benzoic acids, are carried over to the CHP cleavage products during neutralization of the acid catalyst. The presence of such salts in the CHP cleavage products conveyed to a downstream stage of target product fractionation causes a number of serious problems, such as clogging of heat exchange equipment, increased utilization of steam, and most importantly, significantly complicates the processing of undesirable phenol waste products.
The phenol process waste products can be divided into two types:    1. Byproducts formed during a stage of technical grade CHP cleavage, which are collectively called “phenol tars”; and    2. Byproducts formed in preparation and separation of cumene during a stage of AMS hydrogenation to cumene, or during a stage of target AMS production, which are collectively called “aromatic tars”.
Phenol tars are typically mixtures of various compounds, for example, including, but not limited to:                Products of phenol condensation with dimethyl benzene alcohol (DMBA) such as ortho-, metha-, and para-cumylphenols;        Products of DMBA condensation to AMS dimers of three species (dimer 1, dimer 2, and dimmer 3);        Polyphenols;        Acetophenone;        Phenol;        DMBA and AMS;        ortho-cumyl ether and other products of deep condensation of phenol; and        Na2SO4.        
Aromatic tars are most commonly represented by cumene, AMS, and AMS polycondensation products, such as trimers and n-mers of AMS. Wastes of this type are typically formed in processing of a hydrocarbon fraction rich in cumene and AMS, which is fed either to an AMS hydrogenation system, or to a target AMS production system. The hydrocarbon fraction is previously washed thoroughly with an aqueous caustic solution to separate it from phenol. As a result of such hydrocarbon fraction processing, sodium phenate concentrates in the waste products.
The wastes from an AMS hydrogenation stage commonly contain about 10 wt. % cumene, about 40 wt. % AMS, about 10 wt. % butylbenzenes, and the remaining balance consisting of mesityl oxide, phorone, and AMS condensation products.
The wastes from a target AMS production stage commonly consist of about 70-80 wt. % AMS, about 1-2 wt. % butylbenzenes, and the remaining balance (about 20-30 wt. %) consisting of AMS polycondensation products.
It should be noted that aromatic tars may or may not contain salts depending on the type and configuration of processing technology applied to the AMS-containing fraction.
The quantity and composition of phenol process wastes (hereinafter referred to as “PPW”) are to a great extent determined by the selectivity of technologies used at critical process stages. For example, when the highly selective technologies as disclosed in the commonly assigned U.S. Pat. Nos. 6,057,483 and 6,225,513 are utilized, the PPW amounts to 30 kg to 40 kg per ton of phenol, but most of currently existing plants utilizing other process technologies report from 80 kg to even 200 kg of PPW per ton of phenol. This is the reason why processing of the PPW is of great practical importance. However, it is practically impossible to process the PPW (including incineration to yield steam), without can first effectively removing mineral salts (such as Na2SO4) from the PPW, where these salts may range in quantity from 0.1 wt. % to 4 wt. %.
It should be noted that all previously known desalting methodologies, such as disclosed in Russian Pat. No 20577467; U.S. Pat. No. 5,283,376; and U.S. Pat. No. 6,034,282, have only been intended to salt removal from the byproducts of CHP cleavage, (i.e. phenol tar) that are free from aromatic tars (that greatly complicate salt removal).
One previously known commercial approach proposes treatment of phenol tar with 10% sulfuric acid solution at a volumetric ratio of 1:0.5 for a period of sixty minutes. After the treatment period ends, the solution is left to settle for two hours and then the desalted tar containing residues of sulfuric acid flows to a stage of washing (by water) to remove the acid. The washing occurs for thirty minutes and the tar is then subjected to a settling period of three hours. As a result this process is very inefficient and costly. Although, this method is capable of achieving a relatively good desalting degree of 85-90% relative, the use of sulfuric acid results in a number of irresolvable technical problems:                First, sulfuric acid promotes a number of chemical reactions of continued condensation that make the materials very viscous and difficult to handle (in terms of transporting or delivery);        Second, sulfuric acid directly reacts with phenol and phenolics to form various species of phenolsulfonic acids, which cannot practically be washed out by water. As a result, the use of a cracker in the process would abruptly reduce the yield of desirable valuable products, while tar incineration would result in an impermissible release of environmentally harmful compounds, such as SO2 and SO3, in combustion gases; and        Third, the phenol tar must be washed from H2SO4 and phenolsulfonic acids simultaneously—this is an unsolvable dilemma.        
Accordingly, the above-described proposed desalting method has not achieved commercial use, and those who attempted to employ it, inevitably rejected it.
U.S. Pat. No. 5,283,376 proposed phenol tar treatment with an aqueous ammonia solution for simultaneous dephenolation and desalting of phenol tar. However, the use of aqueous ammonia (or amine derivative) solution causes a number of serious problems during operation of this technology, indicated below:                The waste water from a phenol plant utilizing the '376 process would contain a very large concentration of nitrogen compounds, which are impermissible by commonly accepted environmental regulations;        Combustion of phenol tar that contains ammonia or its derivatives leads to formation of nitrous oxides in exhaust gases, which creates another serious environmental concern;        Addition of ammonia or amine derivatives to the desalting unit, increases the pH values of the organic and aqueous phases, which results in an essentially non-demulsifiable emulsion, because a third phase is created between the organic and aqueous phases; and        Cracking of phenol tar that has even a small concentration of ammonia or its derivatives, greatly decreases the yield of desirable valuable products.        
All of the above problems, individually and in conjunction with one another, result in the '376 technology being unfeasible and impractical to implement. Accordingly, for the reasons above, ammonia (amine derivatives) desalting methods based on ammonia (amine derivatives) has not found and has not obtained, and will hardly ever obtain, commercial use.
Referring now to U.S. Pat. No. 6,034,282, a process for desalting of phenol tar by water is disclosed. The '282 process, proposed that an emulsion which formed from water contacting with phenol tar is mixed using commonly known mechanical mixing techniques such as utilization of a rotating anchor stirrer, rotating paddles, reciprocating trays, or a pulsing column. However, it is well known in the industry that such mechanical devices cannot be practically utilized for working with materials of such high viscosity as phenol tar. For this reason, all attempts to overcome the desalting challenge by purely mechanical means by utilization of the mechanical mixing devices have met with failure and were never successfully commercially implemented.
One approach that has achieved some commercial success is disclosed in the commonly assigned Russian Pat. No 20577467. The '467 patent discloses a method of contacting phenol tar with water and diisopropyl ether (“DIPE”) to overcome the desalting problem. This method achieves a very high desalting degree of 85% to 95%, depending on the salt content in the phenol tar. The approach disclosed in the '467 patent is used successfully in commercial practice, where a three-step extraction system reduces salts in the phenol tar from 2.5 wt. % to 20 ppm. However, this method also has certain drawbacks:                DIPE can form explosive and flammable mixtures due to its tendency to form peroxides;        DIPE's very low boiling point and high volatility, handicap its condensation for the purpose of recycling, which accordingly results in significant material losses; and        DIPE's entry into recycle streams of main process materials negatively impacts the quality of the acetone product.        
It would thus be desirable to provide an efficient, stable, and environmentally safe process for removing salts from byproducts (wastes) from a phenol production process.